IOCTLs versus netlink

[Rohan Puri]

On Mon, Sep 2, 2013 at 1:30 AM, Kristian Evensen <kristian.evensen at gmail.com
> wrote:

> On Sun, Sep 1, 2013 at 3:16 PM, Greg Freemyer <greg.freemyer at gmail.com>
> wrote:
> >
> >
> > Kevin Wilson <wkevils at gmail.com> wrote:
> >>Hi,
> >>Can someone please explain why are netlink sockets a better
> >>communication method between kernel space and userspace ?
> >>
>
> Another reason is to make things easier to extend. Adding a parameter
> to a netlink message is as easy as adding an additional netlink
> attribute. User space applications that has not been updated to
> support your change, will not see this parameter as it is unknown to
> them when processing the attributes. Extending an ioctl would mean
> adding new paramteres to the struct that is passed to/from the kernel,
> which will cause all kinds of problems. For example, how to avoid
> overflows when returning it to user space.
>
> -Kristian
>
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Hi,

This should give you a lot of insight
http://people.ee.ethz.ch/~arkeller/linux/kernel_user_space_howto.html

- Rohan
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